Knightley on The Edge of Love

When The Edge of Love gets its premiere in Edinburgh on Wednesday, it will mark the end of a personal journey for scriptwriter - and mother of its star Keira Knightley - Sharman Macdonald.

A longtime fan of Dylan Thomas, she "fell in love" with the Welsh poet's work when she first performed it as a 19-year-old actress.

"When you're an actress, the lines disappear from your head as soon as you pick up a new script," she explains.

"But Dylan Thomas's words never disappeared from my head. The love I had for him, I retained."

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When she had a conversation with film student Rebekah Gilbertson about the night her grandfather, William Killick, stormed into Thomas's home at Cardigan Bay to try to shoot him, it sparked the idea for The Edge Of Love.

Killick's wife Vera was Thomas's childhood sweetheart.

Now Macdonald is preparing to walk down the red carpet with her daughter Keira, who plays Vera.

Work began seven years ago, while Knightley was working on the first Pirates of the Caribbean movie.

"I started writing when we were in St Vincent, with a lot of lime Daiquiris," Macdonald recalls.

"Keira was playing on the beach, she was only 17 and I was feeding off her for Caitlin."

Caitlin was Thomas's wife, and they had a wild and violent relationship.

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Director John Maybury says his leading ladies had no trouble with accents

While that role eventually went to Sienna Miller, Keira was instrumental in getting British director John Maybury on board.

"I read the first draft while I was working on [2005 film] The Jacket with John," the actress says.

"I instantly thought he was the only person who could direct this."

But it took four years of "poems, pink champagne and cakes" before Maybury finally committed to the project.

Cardiff-born Matthew Rhys says he could not have been more excited about playing of the most celebrated Welshmen in modern history.

"There aren't many Welsh people, never mind Welsh icons," he jokes.

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"I loved Thomas's stuff. I even did a piece from Under Milk Wood as part of my audition for Rada. I remember the examiner saying to me: 'That's rather obvious for a Welshman?' I hadn't even thought of that."

But landing the role became a double-edged sword. "The pressure that came with it was fairly enormous," he admits.

Sienna Miller also put herself under pressure to play Caitlin. She was on holiday in Mexico when she got a call from Mowbray telling her to "get out of the sun" after Lindsay Lohan dropped out of the film.

"I had two weeks to prepare before we started filming," she says.

"Normally I would spend a lot more time doing research and getting completely paranoid but I just had to jump, which suited the part because she was quite abandoned."

The Edge of Love has its premiere at the Edinburgh Film Festival on Wednesday. It is released in the UK on 27 June.

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